The code-decoder static 16-bit buffer `st->previoussynth_fx[]` has - in IVAS decoder - its 32-bit version `st->previoussynth_fx_32[]`. This duplication is not needed and the buffer `st->previoussynth_fx_32[]` can be removed. <!--- Below are labels that will be added but are not shown in description. This is a template to help fill them. Add further information to the first row and remove and add labels as necessary.-->